The invention relates to a disc filter and its sector. A disc filter has several essentially triangular sectors that form a relatively thin disc that is rotated in a basin containing a suspension to be filtered. The sector comprises opposing side surfaces with several openings through which liquid filtered from the suspension can enter a flow channel inside the sector and on through a neck section of the sector to the body of the disc filter. Solid matter stays against the outer surface of the sector, from which it is removed to a discharge shaft at the end of the filtering step. The object of the invention is described in more detail in the preambles of the independent claims.
For instance in mining industry, metal processing, chemical industry, and in the processes of foodstuff and pharmaceutical manufacturing, there is a need for solid-liquid filtering, in which liquid and solid particles are separated from a suspension of solid matter and liquid. Mechanical filtering devices of varying operating principles and properties have been developed for solid-liquid filtering, and in these a pressure difference is utilised in the separation of the liquid phase and solid matter phase. The disc filter is an example of solid-liquid filters of this type.
The disc filter comprises a tubular body with essentially triangular sector elements arranged on its outer circumference side by side to form a disc-like structure. Negative pressure is applied inside the sector elements, and the side surfaces of the sector elements act as filtering surfaces that are generally furnished with a filtering fabric. Said filtering surfaces have openings through which the liquid that passed through the filtering fabric enters the sector element to flow under the influence of the negative pressure on to the body of the disc filter. A problem with the present sector elements is that the flow from inside the sector element to the neck section and on to the body is not efficient enough, which weakens the filtering capacity of the filter.